Interpretive Summary: The following interpretive summary refers to an invited oral presentation given at the IAEA/FAO sponsored Consultants Meeting on Genetic Sexing and Population Genetics of the Screwworm, August 2000.
Responsibility for screwworm research at the USDA-ARS-Midwest Livestock Insects Research Unit (MLIRU) at Lincoln, NE began in 1991. A state-of-the-art biosecurity facility, completed in 1994, is where all screwworms are reared. Of the four scientists in the MLIRU, two work on screwworm. Iso-enzyme analyses are capable fof identifying screwworm samples and showing genetic variability in screwworm populations but it is a cumbersome technique. PCR-RFLP analysis of mtDNA indicated that this technique was valuable for identifying screwworm from other species but was not well suited for quantifying genetic variability. RAPD-PCR analysis showed value in identifying screwworm from other species and promise for quantifying genetic variability across the geographic range of screwworm. Monoclonal antibodies against all stages of screwworm were isolated and a procedure established that allows the development of a test-kit, for use in the field, which is capable of identifying all stages of screwworm from other fly species. Techniques have been developed for the cryopreservation of screwworm eggs, allowing for efficient genome preservation. Finally, all extant screwworm strains at MLIRU were bioassayed, levels of insecticide tolerance were determined, and selection is progressing to establish insecticide resistance in one strain. Once resistance is established, classical genetic techniques (i.e. translocation of resistance 'gene' to the Y-chromosome) will be used to develop a genetic sexing strain. Concurrently, we intend to screen screwworm for temperature sensitivity (temperature sensitive lethals) and, if found, use those 'genes' in a classical approach to developing a genetic sexing strain. The most competitive genetic sexing strain(s) would be evaluated for use in the screwworm eradication program.

Technical Abstract:
The following technical abstract refers to an invited oral presentation given at the IAEA/FAO sponsored Consultants Meeting on Genetic Sexing and Population Genetics of the Screwworm, August 2000.
Responsibility for screwworm research at the USDA-ARS-Midwest Livestock Insects Research Unit (MLIRU) at Lincoln, NE began in 1991. A state-of-the-art biosecurity facility, completed in 1994, is where all screwworms are reared. Of the four scientists in the MLIRU, two work on screwworm. Iso-enzyme analyses are capable fof identifying screwworm samples and showing genetic variability in screwworm populations but it is a cumbersome technique. PCR-RFLP analysis of mtDNA indicated that this technique was valuable for identifying screwworm from other species but was not well suited for quantifying genetic variability. RAPD-PCR analysis showed value in identifying screwworm from other species and promise for quantifying genetic variability across the geographic range of screwworm. Monoclonal antibodies against all stages of screwworm were isolated and a procedure established that allows the development of a test-kit, for use in the field, which is capable of identifying all stages of screwworm from other fly species. Techniques have been developed for the cryopreservation of screwworm eggs, allowing for efficient genome preservation. Finally, all extant screwworm strains at MLIRU were bioassayed, levels of insecticide tolerance were determined, and selection is progressing to establish insecticide resistance in one strain. Once resistance is established, classical genetic techniques (i.e. translocation of resistance 'gene' to the Y-chromosome) will be used to develop a genetic sexing strain. Concurrently, we intend to screen screwworm for temperature sensitivity (temperature sensitive lethals) and, if found, use those 'genes' in a classical approach to developing a genetic sexing strain. The most competitive genetic sexing strain(s) would be evaluated for use in the screwworm eradication program.